Argon plasma coagulation (APC) or argon beam coagulation (ABC) is a known surgical technique for controlling surface bleeding in a manner that does not require physical contact between a surgical probe delivering the plasma and the lesion. APC can be performed endoscopically, whereby a jet of argon gas is directed through a probe passed through an endoscope. Ionization of the argon gas as it is emitted creates the plasma that causes coagulation.
To strike plasma it is desirable to have a high electric field (e.g. high voltage or high impedance condition). Accordingly, it is necessary to set-up a high impedance state in order to enable the high voltage (high electric field) necessary to break down the gas to generate plasma. In one embodiment discussed in WO 2009/060213, a high voltage (high impedance) condition is set up using a flyback circuit that uses a low frequency (e.g. radiofrequency) oscillator circuit and a transformer whose primary winding is connected to the low frequency oscillator circuit by a suitable driver and switching device (e.g. gate drive chip and a power MOSFET or BJT). The arrangement generates high voltage pulses or spikes which strike or otherwise initiate the plasma. Once struck, the plasma may be maintained by a supply of microwave energy.